Containers for long-term storage have to be mechanically stable, resistant to corrosion and must be tightly closed. The vessel of the container is therefore made of steel or cast iron containing nodular graphite in order to ensure the mechanical stability of the container. It is preferable to utilize cast iron containing nodular graphite of a grade such as GGG-40 for making thick-walled container vessels because spheroidal cast iron exhibits especially high strength and toughness. The grade GGG-40 is listed in German nodular cast iron specifications.
The corrosion-resistance of steel or cast iron is inadequate for the purpose of long-term storage. Accordingly, it has been suggested to apply a corrosion-resistant protective outer layer to a container vessel made of steel or cast iron. This protective layer can be made of ceramic or graphite.
It has been suggested to produce the vessel of a container from a thick-walled layer of steel with an outer layer of zircaloy-2. The thin coating of corrosion-resistant zircaloy-2 is pulled over the inner base structure of the vessel and is shrunk thereon. Alternatively, the zircaloy-2 can be plated to the vessel base structure. The coating of the vessel base structure with zircaloy-2 is very expensive and requires a major engineering effort. Shrinking or plating the outer zircaloy layer onto the vessel base structure does not provide a failure-free bond between the two layers of the container. The zircaloy layer is relatively thin so that weld and material failures constitute serious disadvantages for the integrity of the sealing of the container with respect to the ambient.